Inactive position centering mechanism for sewing machines



Aug. 26, 1969 G. B, sARAY 3,463,103

INACTIVE POSITION CENTERING MECHANISM FOR SEWING MACHINES Filed May 24, 1967 2 Sheets-Sheet 1 enige Sara/y WWK-3% Wm@ @mi Aug. 26, 1969 G. B. sARAY l 3,4631103 i INACTIVE POSITIN CENTERING MECHANISM FOR SEWING MACHINES l Filed May 24, 1967 A' sheets-Sheet 2 fwn/rox 3g Geary@ Suray United States Patent O 3,463,103 INACTIVE POSITION CENTERING MECHANISM FR SEWING MACHINES George l?. Saray, Stamford, Conn., assigner, by mesne assignments, to Ivanhoe Research Corporation, New

York, NY., a corporation of Delaware Filed May 24, 1967, Ser. No. 640,990

Int. Cl. DSh 69/22 US. Cl. i12-219 2 Claims ABSTRACT F THE DISCLOSURE A control device for sewing machines is provided so that the machine will always stop operation and become latched only at a known inactive position, shown here as the upper limit of the needle stroke, i.e., its top dead center position. The device causes the needle to stop when it is removed from the workpiece and to remain locked in that inactive position until the machine is started again. The automatic device operates by using a second motor which produces motion of the needle after the primary motor is stopped, until a predetermined position of the main shaft of the sewing machine is reached. The second motor is controlled by a cam and cam follower; it is disengaged during normal operation of the sewing machine.

Background of the invention This invention is for use in the sewing machine field. It is a control device which may be added to existing sewing machines or incorporated into the structure of the machine when built.

When a sewing machine is operated by hand, it is necessary to remove the needle from the workpiece before the workpiece can either be moved to a new position under the needle or removed altogether from the machine, except when sewing off. This has usually necessitated hand rotation of the machines main shaft to bring the needle to its upper or any other predetermined position. This eifort delays operation of the machine and so decreases efficiency.

In those instances where a sewing machine is automatically operated, with programmed feed and removal of fabric workpieces, the needle must always be held in a withdrawn position when stopped. Otherwise, movement or removal of the fabric workpiece could not take place in accordance with the program.

Though other devices have been made to control needle position when the machine is stopped, these devices have tended to be cumbersome and relatively expensive. It is believed the present device accomplishes this function more simply, economically, and expeditiously than have previous structures.

Description of the drawings The invention is shown in the attached drawings, as follows:

FIG. l is a perspective view of a sewing machine, having a portion of the covering shell cut away to show the mechanism of this embodiment of the invention.

FIG. 2 is an end elevation, with the cover removed showing the elements of the present device. The device is shown in the disengaged position, as would be the case during normal operation of the sewing machine.

FIG. 3 is a perspective view of the cam of the control unit removed from the device.

FIG. 4 is an end elevation showing a portion of the structure depicted in FIG. 2, but with the cam follower in the engaged and locked position.

ICC

FIG. 5 is a schematic circuit diagram of the circuit used in the operation of this device.

Description of the invention FIG. 1 is a perspective view of a sewing machine of standard design, but having the control unit of the present invention incorporated in it.

The machine includes a base 1 for supporting the workpiece to be sewn, a machine body or frame 2, and a driving belt 3 connected with a driving means (not shown in FIG. l) such as an electric motor which is referred to herein as the primary driving motor. The belt 3 rotates a main shaft 4 of the sewing machine, which in turn drives the needle 5 up and down. This shaft 4 causes needle 5 to move up and down through the throat opening 6 in a base plate 7 in the customary manner to form stitches in a workpiece. Since the needle 5 is positively interengaged with the shaft 4, the motion and position of needle 5 is at all times directly related to the angular position of the shaft 4.

In normal operation of an ordinary sewing machine, the needle will stop at a random position relative to the base plate when the motor is stopped. The needle may be up, dov/n, or at any position in between.

The control unit 8 of the present invention is mounted at the end of the frame 2 between belt 3 and frame 2. It is positioned to be in operative relationship with drive shaft 4. This unit S is enclosed within an outer casing 11.

Details of the structure of control unit 8 are best seen by reference to FIG. 2. Mounted on shaft 4 are a cam 13, a pulley wheel 1S, and a gear 16. The pulley Wheel 15 receives belt 3 and so transmits the motion of this belt to shaft 4. As shown on the drawing, the motion of belt 3 is such that pulley 15 and shaft 4 rotate in a counter-clockwise direction.

Sensing means 1i) having a cam and follower are provided for sensing the angular position of the main shaft 4. The sensing means includes the cam 13, shown separately in FIG. 3, which cam is adjustable 360 on the shaft. Cam 13 has a surface 14 with a radius which decreases along its perimeter in the clockwise direction. It is so designed that the radius decreases relative to a cam follower as the cam rotates in its normal direction (counter-clockwise in FIGS. Zand 3). At the point where the radius is smallest there is a notch 17 (FIG. 3) of even lesser radius dimensioned to receive the cam follower and thus to lock the cam in that position. Adjacent this notch 17 is a radially extending shoulder wall 18, providing a discontinuity and leading to the section of cam 13 having the greatest radius. The shoulder or abutment 18, as will be described below, acts as a stop which is engaged by the cam follower.

The sensing means 1t! also includes the cam follower 29 which is in the form of a lever pivotally mounted on the base plate of frame 2 at a pivot 21. yIt is positioned so that it may be in operating relationship with cam 13 during periods when the sewing machine is not operating.

At its upper end the follower 2t) has a cam-engaging latch 22, spring pressed against cam surface 14. Latch 22. is dimensioned to tit snugly and become engaged within the notch 17, when the latch 22 and notch 17 are in alignment.

Control unit 8 also includes secondary or auxiliary driving means, such as a motor 29, for the sewing machine 2. The auxiliary driving means is adapted to rotate the main shaft 4 to move the needle from any random position to a predetermined inactive position. The auxiliary driving means includes a motor, normally operating, and an electrically controlled clutch 31 to engage or disengage the motor from a gear train.

Associated with the secondary driving means are the gear 16 mounted on shaft 4, as previously described, and an engageable gear train made up of gears 25, 26 and 27 (FIG. 4). Gear 27 is mounted on and driven by the axle 28 of an auxiliary motor 29; gears 25 and 26 are mounted on a gear arm 35. Gears 25, 26 and 27 are always in engagement one with another, but the gear 25 may be engaged with or disengaged from the gear 16, as described below. FIGURE 2 shows gear 25 disengaged from the gear 16, and FIGURE 4 shows them engaged.

Gear arm 35 is pivotally mounted on the base of body 2 at pivot 36 which pivot also forms the axis of gear 26. Gear 25 is mounted on gear arm 35. Arm 35 includes an upwardly extending arm 37 and a downwardly extending arm portion 38. Thus, swinging movement positions gear 25 so that it is either engaged with or disengaged from gear 16.

Mounted below the shaft 4 and inwardly from the belt 3 is spring return air cylinder 43 including a pneumatically actuated plunger 42 adapted to be moved by a pneumatic cylinder 43. A source of air under pressure for actuation of cylinder 43 is indicated at 44. A solenoid valve 73 (FIG. 5) controls air input to supply line 44. Cylinder 43 may, alternatively, be operated by vacuum. Plunger 42 is positioned for sliding movement back and forth horizontally, and it is pivotally connected at its outer end to the arm 38 of gear-supporting arm 35. Arm 35 is pivotally mounted on frame 7. Thus, action of cylinder 43, actuated by the supply 44, will cause arm 35 to pivot counterclockwise (extended plunger position) and clockwise (retracted plunger position) about pivot 36 and cause engagement and disengagement of gears 25 and 16.

Thus, the gears 25 and 16, and the gear train 27, 26, 25 together with the gear arm 36, 37, 38 provide means to engage the auxiliary driving means 29 with the main shaft 4. The plunger 42, cylinder 43, air supply line 44 and the associated part of the electrical circuit provide means to actuate and so couple the auxiliary driving means 29 with the needle.

The gear arm 35 and cam follower lever 20 are interconnected by a link 50, this link being pivotally secured to lower portion 38 of lever arm 35 at a pivot point 51. The link is slidingly engaged with the follower lever 20 by a pin 52 secured to the lower portion of follower 20 and projecting through a horizontal slot 53 in link 50. Link 50 is of such length and slot 53 so positioned on link 50 that when the lower portion 38 of arm 35 is in its lefthand (disengaged) position link 50 presses against pin 52 and so forces the lower portion (below the pivot 21) of follower lever 20 to the left, causing the upper portion of the follower 20, and latch 22, to be moved away from the cam 13. At the same time this moves arm 35 to disengage gear 25 from gear 16. Thus, the control unit is in its inoperative or disengaged position. This occur when plunger 42 has been retracted into pneumatic cylinder 43, that is, plunger 42 is in the left-hand position as it is shown in FIG. 2.

Also mounted on the link 50 is a spring 5S having one end secured to link 50 adjacent to pivot 51. The other end f spring S is secured to the pin 52. Spring 55 is of such length that the lower portion of the follower lever is spring pressed to the right, causing its upper portion and its cam latch 22 to be pressed to the left, to the extent that motion of the pin 52 can occur within the slot 53.

In FIG. 4, plunger 42 is shown in its extended position. Now gear is engaged with gear 16, and the follower lever 20 is given a counter-clockwise moment due to the force of spring 55 urging the cam follower against the contact surface of the cam. Since link 50 has been moved to the right, the slot 53 has been shifted to the right sufriciently far to allow the cam latch 22 to be pressed against contact surface 14. The control unit is now in the engaged or operative position.

Secured to the lower end of lever 20 and extending substantially horizontally to the left (FIGS. 2 and 4) is a switch actuator element 60 with an adjustable switch actuating button 61. This button is position in operative association with the trigger of a normally-closed microswitch 62. FIG. 2 shows this switch in its normally closed position, and FIG. 4 shows the trigger of switch 62 being pressed by the button 61 and, therefore, the switch 62 is open.

A schematic circuit diagram of the control unit is shown in FIG. 5. Power input is supplied through leads 70 and 71 and through a main power switch in the input lead 71 Auxiliary .motor 29 (always operating) is across the leads. Double-throw switch 74 is the on-off switch for the sewing machine, such as a foot treadle. In the on position the circuit is closed from leads 70 and 71 through main motor 72. In the off position the circuit is closed through time-delay 32. Once switch 32 has acted, it is also closed through electric clutch 32 and air control solenoid 73, with normally-closed micro-switch 62 in series with clutch 32. Thus, when switch 74 is moved to the off position, time-delay switch 32 is energized and, after the pre-set delay, clutch 31 and solenoid 73 are connected.

The switch 74 is the main control switch for the sewing machine. It can be actuated either by hand or foot, if the machine is manually operated; or, alternatively, it may be automatically controlled if the machine is automatic and/or has been programmed. The main switch 74 and solenoid valve 73 comprises first circuit means to actuate the sensing means 10 when the primary driving means 72 is deenergized. The norn1ally-closed switch 62 which is opened in response to the cam follower lever 20 seating in the notch comprises second circuit means which deactuates the auxiliary driving means 29 when the needle 5 has been. moved to the predetermined desired inactive position.

When the sewing machine is off, switch 74 will be in the right-hand position as shown in FIG. 5, thus disconnecting the main driving motor 72. When the machine is operated, switch 74 is thrown into the left-hand on position, energizing motor 72. It can be seen that primary motor 72 and clutch 31 cannot be energized in unison.

Use of the time-delay switch 32 is to allow the drive shaft 4 to come to rest before starting the control device. If desired, this may be a slip clutch (to provide for instances in which the shaft has not come to rest).

Operation of the control device In discussing the operation of this automatic inactive positioning control unit, it will be assumed that the machine is being operated by manual control, i.e., in the conventional manner. The only difference between manual operation and automatic operation, insofar as the present invention is concerned, is the type of control (manual or automatic) to which switch 74 is responsive.

Starting this example with the machine stopped, and assuming that needle 5 is raised above plate 7, the workpiece to be sewn is placed on plate 7 under needle 5 and under the presser foot. Switch 74 is then moved to the left-hand position (FIG. 5), completing the circuit for energizing motor 72. Motor 72 drives belt 3 which in turn drives shaft 4 so that the sewing machine then operates to form stitcher in the normal manner.

While motor 72 is energized, the solenoid valve 73 will be de-energized shutting olf the air applied to line 44. Spring-pressed plunger 42 will move into cylinder 43 (retracted position) positioning gear arm 35 in its extreme clockwise position, as shown in FIG. 2, and will hold the gear 25 disengaged from gear 16. Clockwise motion of arm 35 will act through link 50 and push pin 52 of cam follower 20 to move follower 20 in a clockwise direction, thus positioning the cam latch 22 to a position remote from the surface 14 of cam 13. Accordingly, the control unit 8 is in the inoperative position, having no effect upon the motion of shaft 4, and, therefore, allowing this shaft 4 to rotate, and the sewing machine to operate, in the normal manner. Switch 62, not being pressed by button 60, will be in its normally closed position.

When the particular sewing operation is interrupted or terminated, as by completion of such operation, for example, the motor 72 will be stopped by throwing or positioning switch 74 to the right-hand or off position (FIG. 5). With this switch thus positioned the primary driving circuit will be opened and time-delay switch 32 energized. After delay, solenoid 73 will be energized, connecting line 44 to a source of air under pressure, which pressure forces plunger 42 to the right, to its open or extended position. The action by plunger 42 will give a counter-clockwise motion to arm 35, about pivot 36, causing gear 25 to engage with gear 16. Through the action of link 50 and spring 55, the cam follower is subjected to a spring-pressed moment in the counter-clockwise direction, forcing the latch 22 against the surface 14 of cam 13. It should be realized, in this respect, that cam latch 22 will press upon whatever portion of the surface 14 happens randomly to be beneath it when the action of the plunger 42 occurs.

Stopping of the machine by de-cnergized motor 72 (by re-positioning double throw switch 74) results in connecting time-delay switch 32 and thus clutch 31 and solenoid 73 to power supply leads 70 and 71. When motor 29 is engaged by clutch 31, it will drive gear 27 in a clockwise direction (as viewed in FIGS. 2 and 4) and thus rotate gears 27, 26 and 25 of the gear train. Gear 25, now being engaged with gear 16, will drive gear 16, and shaft 4 will rotate in a counter-clockwise direction as viewed in FIGS. 2 and 4. This is the same direction that the shaft 4 turned when driven by belt 3 from the primary motor 72.

It should be realized that the shaft 4, and thus the needle S, can be in any random position when the main driving motor 72 is stopped. Assuming that the position is other than that shown in FIG. 4 (i.e., the latch 22 is not within notch 17) then the switch 62 will remain closed, and the secondary motor 29 will be energized as described. The gear 16 will be driven in a counter-clockwise direction through the coupled gear train, thus rotating shaft 4 in a counter-clockwise direction, and so revolving the surface 14 of cam 13 under the latch 22. The latch 22 is spring-pressed against the cam surface 14 during this revolution of the cam 13.

When cam 13 has rotated suiciently so that cam notch 17 cornes directly under the latch 22, cam latch 22 will be pivotally forced into notch 17 by spring 55, as shown in FIG. 4. The shoulder 18 serves to abut against the face of latch 22, stopping the rotation of the shaft 4. When the latch 22 seats in the notch, the cam follower 20 pivots about pivot 21 in a counter-clockwise direction drawing the switch actuating button 61 against the trigger of the switch 62, opening it and so disengages the drive clutch 31 for discontinuing the drive action of the motor 29.

Due to the positive inter-connections in the sewing machine between the drive shaft 4 and the needle 5, there is a direct inter-relationship between the angular position of the drive shaft 4 and the vertical position of needle 5. There is a given position of needle 5 for every angular position of drive shaft 4. Accordingly, cam 13 can 'be mounted on drive shaft 4 at any angular position that when the latch 22 seats in notch 17 needle 5 is at the desired inactive position, which may be at its top dead center position, that is, at its highest point of its stroke.

It will be seen that the device of my invention will rotate shaft 4 every time that the machine is stopped unless and until shaft 4 is at the angular position corresponding with the highest position of needle 5. Rotational motion will then be stopped and the unit 8 de-energizes the sewing machine and locks the machine in the particular angular position with the latch 22 interengaged with notch 17. With the needle in its raised position, the workpiece can be removed and a new one placed on the machine without interference of the needle.

The needle will remain locked in its inactive position until the operator reverses or repositions switch 74 thereby completing a circuit and energizing the primary motor 72 (by positioning switch 74 to the left-hand or on position, as seen in FIG. 5). Completion of this circuit =also de-energizes solenoid 73, releasing pressure from line 44 and thus causing pneumatic plunger 42 to move to the left or retract. This action rotates arm 35 in a clockwise direction about pivot 36 through linkage 50, and arm 20 is pivoted clockwise about pivot 21, thereby disengaging cam latch 22 from the notch 17. As described above, the control unit 8 is now in its disengaged position. The sewing machine cycle may then be repeated.

In summary, the sequence of operation, upon stopping the sewing machine, are:

(1) Switch 74 is turned to off position.

(2) Time delay switch 32 is connected and so is on and commences timing while main shaft 4 comes to rest.

(3) Time delay switch 32 then actuates:

(a) Solenoid 73, so that air enters cylinder 43 and moves plunger 42 and arm 3S to press latch 22 against cam 13, and to press gear 25 against shaft gear 16.

(b) Clutch 31, so that motor 29 engages the gear train to rotate shaft 4.

(4) Shaft 4 and cam 13 rotates until latch 22 engages with notch 17, stopping the shaft at its predetermined position.

(5) The motion of latch 22 opens switch 62, disconnecting clutch 31.

(6) The workpiece is removed and/ or -a new one added.

(7) Switch 74 is turned to on, disconnecting solenoid 73, starting the sewing machine, and so starting the cycle again.

The terms and expressions which have been emploped are used in a descriptive and not `a limiting sense, and there is no intention of excluding equivalents of the invention described.

What is claimed is:

1. A control mechanism for use with a sewing machine to automatically cause the needle to stop only at a predetermined inactive position and to automatically lock the needle in said inactive position, said sewing machine including a frame, a needle, a main shaft rotatably mounted on said frame, said main shaft 'being operatively coupled to the needle for driving the needle up and down, and primary driving means for rotating said shaft during sewing operation, said control mechanism comprising a rotatable cam and a first gear both mounted on said main shaft, said cam having a peripheral contact surface with a notch in said peripheral surface, a cam follower movably mounted on said frame, said cam follower including a latch adapted to enter said notch for locking said main shaft to lock said needle in said predetermined inactive position, said cam follower being movable between an inactive position in which said latch is withdrawn from said peripheral surface `and an active position in which said latch is urged against said peripheral surface, auxiliary driving means mounted on said frame, a clutch connected to said auxiliary driving means, a second gear mounted on an axis on said frame, said second gear being driven through said clutch about said axis by said auxiliary driving means when said clutch is engaged, a gear arm pivotally mounted on said frame to swing about said axis, a third gear rotatably mounted on said gear arm and engaged with said second gear to be driven thereby, said gear arm normally being in an inactive position in which said third gear is spaced from said first gear and being swingable about said axis into an engaged position in which said third gear meshes with said first gear, actuating means connected to said gear arm for swinging said gear arm from its inactive position to its engaged position, on-oif control means for shutting olf said primary driving means to stop a sewing Operation, time-delay means responsive to the shutting olf of said primary driving means for operating said actuating means to swing said gear arm to its engaged position, spring means connected from said gear arm to said cam follower for urging said cam follower into its active position when said gear arm is in its engaged position, and switch means connected to said clutch, said switch means being responsive to entry of said latch into said notch for disengaging said clutch when said latch 10 has locked the needle in said predetermined inactive position.

2. A control mechanism for use with a sewing machine as claimed in claim 1, in which a mechanical link for moving said cam follower into its inactive position when said gear arm moves to its inactive position.

References Cited UNlTED STATES PATENTS 990,999 5/ 1911 McGuire et al. 2,612,127 9/ 1952 Hayes. 2,911,930 11/1959 Taylor 112--219 2,942,564 6/ 1960 Larys et al. 3,195,488 7/ 1965 Winberg. 3,320,914 5/1967 Adams.

H. HAMPTON HUNTER, Primary Examiner U.S. Cl. X.R.

extends between said gear arm and said cam follower 15 192/-142 

